The present invention concerns fastener removal. More particularly, but not exclusively, this invention concerns a method for removing a fastener from a component. The invention also concerns a cap for use in removing a fastener from a component.
US 2012/0055293 discloses a tool for removing a seized fastener from a component. The tool comprises a rod driver and one or more interchangeable sockets. The sockets connect to one end of the driver and have different openings at their front ends for connecting over different size/shape bolt heads. The driver is designed to secure a pneumatic hammer at its other end. Shock waves are then sent into the bolt shank and thread areas via axial blows from the pneumatic hammer. The tool allows impacts to be centred on the bolt head without damaging the bolt head and without the driver jumping off the bolt.
However, the tool can only be used on bolts where the bolt head protrudes from the component. In other words, it cannot be used for sunken bolt heads or fasteners that do not have a bolt head, or similar.
Another method for removing a bolt is also known. This method involves drilling a hole through the centre of the bolt head (which may be sunken) and down into the shank of the bolt. The hole is then tapped to provide it with an internal thread. A mandrel is then screwed into the internally threaded hole, a spacer bush placed over the mandrel and a hydraulic puller tool is used to pull on the mandrel and thereby pull the bolt out from its hole in the component.
The bolt (still attached to the mandrel) is then placed back in the hole in the component in order to remove the bolt sleeve still in the component hole. A sleeve removal cap is then screwed onto the exposed tail of the bolt. The spacer bush is then placed over the mandrel and the hydraulic puller tool is used to pull the mandrel, and thereby the bolt, sleeve removal cap and the sleeve from the component hole.
A disadvantage of this method is that, although it can be used for fasteners with sunken bolt heads, it is very time consuming. For example, it can take approximately 5 hours to remove one bolt using this method. In addition, it requires drilling through and tapping inside a bolt, which cause damage to the bolt and introduce health and safety considerations. In addition, there is a risk of damage to the component itself. Furthermore, the pressure required to drill through the bolts can cause damage to the drill bits used.
The present invention seeks to mitigate the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved method for removing a fastener from a component.